Apparatus and method for machining workpieces

ABSTRACT

Disclosed are apparatus and methods for manufacturing complex gears includes the creation of a data set to control a robotic machine tool enabling the tool to machine the contours of the gears accurately after the gear has been cut. Each gear is mounted to an indexable chuck which is used to position the gear for machining operations such as chamfering and deburring that heretofore have been done by hand. A machine cabinet allows debris from machining to be recovered by a vacuum-operated system and an air-cooling system cools the gear during machining without requiring the use of cooling oils or other liquids.

RELATED APPLICATION

This application claims the benefit of provisional patent applicationSer. No. 60/461,080, entitled “Apparatus and Method for MachiningWorkpieces”, filed Apr. 8, 2003.

FIELD OF INVENTION

The present invention relates generally to computer-directed machiningapparatus and, more particularly, to apparatus and methods for carryingout such machining operations as chamfering, deburring, reaming, honingand polishing forged, extruded or machined metal parts.

BACKGROUND OF THE INVENTION

It is a common industrial technique to use computer-controlled andcomputer-set cutting machines to cut complex shapes into solid metalblanks. One example of a typical and widespread use of this technique isthe manufacture of gears, such as spiral and hypoid bevel, spur andhelical gears used in automobiles and trucks. After the gears aremanufactured they must be deburred to remove excess metal flashing orburrs and may also undergo chamfering to finish the individual gearteeth.

Automated chamfering and deburring machines are known for relativelysimple gear configurations, such as those made and sold by RedinCorporation of Rockford, Ill., Mutschler Technologies, Inc. of NorthRidgeville, Ohio and GMI of Independence, Ohio. Other machines have beendeveloped to chamfer and deburr more complex gear shapes such as spiralbevel and hypoid gears. One such machine is made and sold by the GleasonWorks of Rochester, N.Y., but can only machine the drive side of eachgear tooth. This is acceptable and satisfactory for automotiveapplications but not for such complex gears such as aerospace-qualityspiral and hypoid bevel gears, which require precise chamfers on alltooth edges. Such complex aerospace gears are often made in complexgeometric shapes and require precision machining to extremely precisetolerances in order to perform satisfactorily. They must also be aslightweight as possible, meaning the gear teeth are made as small aspossible yet must withstand maximum load or torque because they areoften incorporated in the drive trains of aircraft such as airplanes,helicopters and spacecraft such as the space shuttle.

In an article entitled, “Robotic Automated Deburring of AerospaceGears,” written by Michael Nanlawala, which appeared in theJanuary/February 2001 issue of Gear Technology magazine, the authordescribes in detail some of the post-manufacturing processes that arecritical to the proper manufacture and performance of complex aerospacegears. In particular, the author states: “Machining processes, such asmilling, drilling, turning, hobbing or other gear tooth cuttingoperations, create burrs on the edges of metal parts when the cuttingtool pushes material over an edge rather than cutting cleanly throughthe material. The size, shape and characteristics of the resulting burrsdepend upon a number of process factors, such as tool material and itshardness, tool sharpness, tool geometry, cutting forces, ductility ofthe material being machined, the speed and feed of the cutting tool, andthe depth of cut. A subsequent deburring operation is generally requiredafter those machining processes to remove loose burrs from the machinededge and to apply a chamfer to remove the sharp corners. In addition tothe removal of loose burrs, the deburring of the edge produces benefits,such as the removal of sharp edges, increasing the ease of assembly,prevention of edge chipping or breakage, and improvement of air [sic]flow over the edge of rotating parts. Removing sharp edges by deburringand chamfering also eliminates the possibility of stress concentrationand increases fatigue life.”

Divots, nicks or cuts formed by uneven or discontinuous chamfering cancreate stress risers in the manufactured gear which can lead topremature failure of the gear. Heretofore, the most common method ofremoving burrs and applying chamfers to gear teeth has been the use ofmanual machining tools applied by a workman to the gear surfaces.Because complex gears have many such surfaces and because theintersection of these surfaces often requires reversal and repositioningof the hand grinder in order to create a continuous chamfer,hand-working such a gear is a laborious and time consuming andrelatively imperfect technique. It is not uncommon to have a 30 to 40%rejection rate for hand-chamfered and deburred gears.

As reported by Nanlawala, manual deburring has been associated withsafety hazards arising from such injuries as cuts, splinters, burns,bruises and eye injuries as well as arthritis, carpal tunnel syndromeand pulmonary illness caused by the inhalation of material ground fromthe gear blank. Chamfering and deburring a workpiece such as a gearhousing can take up to six hours of manual labor with less thanreproducibly accurate results.

A typical process used to manufacture aerospace quality gears usescomputer controlled or manually set manufacturing or hobbing machines tocut the gear profile from a solid metallic blank. Examples of such amanufacturing tool are the gear cutting machines manufactured by theGleason Corporation of Rochester, N.Y.

Attempts have been made to use computer-controlled machining tools toperform the chamfering and deburring operations presently being donemanually. For example, in the Nanlawala article, a number of tools andcomputer-controlled tool heads are proposed for use in automaticchamfering and deburring operations. None of these combinations ofhardware, computer software and tools has proven to be successful on acommercial scale. In particular, Nanlawala focuses on the use offorce-controlled machining heads. Machining performed by such heads iscontrolled by the amount of force required to keep the head in contactwith the surface or edge to be machined. In order to carry out such anoperation, Nanawala describes the use of path programming to teach acomputer-controlled robotic machining arm the path required to befollowed about the gear periphery in order to carry out the deburringand chamfering operations.

Path programming as described by Nanlawala uses the “teach pendant”method which requires physically moving the robotic cutting head to aselected point along the gear periphery and recording the position ofthat point in the computer's memory as well as the orientation of therobotic arm required to machine that point along the gear periphery.

Next, the machining head is moved to a second point and, again, thelocation of this point as well as the orientation of the machining headis recorded. When a sufficient number of these points are so recorded,it should then theoretically be possible to use the program created tosuccessfully chamfer and deburr the gear. In practice, this trial anderror procedure is extremely time-consuming, requires frequentrepositioning to adjust the angle of the machining tool to the workpieceand results in wasted workpieces. Moreover, it must be repeated for eachgear type whenever a new run of gears is manufactured.

A desirable alternative to the teach pendant technique would be theability to “model” the gear surfaces in a computer and to use the modelto control the machining operation. Computer modeling of complex gearssuch as spiral bevel aerospace gears is described in an article entitled“New Gear Software” which appears in the January/February 2003 issue ofGear Technology magazine. However, use of the software is limited tocreating on-screen solid model depictions of the gears and allowing gearassemblies to be virtually assembled to verify how they fit together.The author of the software is reported as saying: “ . . . he doesn'trecommend his latest version for creating the geometry needed tomanufacture a spiral bevel gear by traditional metal-cutting methods.”Thus the “New Gear Software” models the gear blank to create a computerimage but cannot be used to cut or machine the gear blank.

Examples of the need for chamfering and deburring and attempts atcomputer-controlled machining operations to carry out these operationsare well represented in the prior art.

U.S. Pat. No. 5,091,861 (Geller et al) teaches and describes a systemfor automatic finishing of machine parts in which the inventors describethe desirability of an automatic, computerized finishing system formachined workpieces and, in particular, state that “Automaticcomputerized systems for deburring are not known to the inventors.”(col. 1, lines 25-27). This reference teaches the use of solid modelingtechniques to deburr straight edges.

U.S. Pat. No. 5,146,670 (Jones) teaches and describes profiling anddeburring of workpieces having straight edges.

U.S. Pat. No. 5,675,229 (Thorne) teaches and describes apparatus andmethods for adjusting robot positioning which describes in detail theteach pendant method used to generate data sets.

U.S. Pat. No. 6,079,090 (Ongaro) teaches and describes a numeric-controlmachine tool for turning and hobbing mechanical parts which states atcol. 4, lines 26-32 that the apparatus is capable of chamfering but doesnot describe how the tool is controlled to carry out the chamfering andincludes no discussion of complex gear shapes.

U.S. Pat. No. 5,785,771 (Mitchell Jr., et al.) teaches and describes amethod for manufacturing precision gears. At col. 1, lines 26-37, theinventors describe with particularity the manufacture of such gears andthe advantage to reducing or eliminating the number of scrappedworkpieces resulting from said manufacture. At lines 61-64 of col. 1,the inventors confirm the value of the chamfering operation by statingthat chamfering reduces stress concentrations in the completed gear.

U.S. Pat. No. 6,074,481 (Bittner, et al.) teaches and describes amasking tool for manufacturing precision gears and method for makingsame.

U.S. Pat. No. 6,080,349 (Bittner, et al.) teaches and describes amasking tool for manufacturing precision gears and method for makingsame. This patent is a division of the '41 patent and furtherparticularizes the masking technique described therein.

U.S. Pat. No. 5,810,522 (Parker) teaches and describes a hand-held baredging tool and support therefor, an example of a hand drill accessoryused for hand deburring and chamfering of bar stock.

U.S. Pat. No. 5,154,533 (Baumstark) teaches and describes an apparatusfor chamfering and deburring the end edges of a toothed production gear,an example of an apparatus specifically designed to hand-chamfer anddeburr the outer edge of a specific gear. U.S. Pat. No. 4,412,765(Occhialini) teaches and describes an apparatus for facilitatingchamfering/deburring tool and gear meshing, an example of anothernon-automated apparatus designed to treat specific gears.

U.S. Pat. No. 4,334,810 (Behnke et al) teaches and describes a geardeburring apparatus and method. This reference uses a non-automateddrive gear to mesh with the gear workpiece to carry out the machiningoperation needed to deburr the gear. U.S. Pat. No. 4,068,558 (Loos)teaches and describes a device for deburring or chamfering of the faceedges of gears, including helical gears, in which a series of guidediscs and cutters specifically designed for each different gear is usedto chamfer or deburr the axial edges of the gear teeth.

U.S. Pat. No. 5,960,661 (Massee) teaches and describes an apparatus fora workpiece showing a computer controlled apparatus moveable in twodimensions which does not describe chamfering or deburring.

U.S. Pat. No. 5,901,595 (Massee) teaches and describes an apparatus formachining a workpiece which is a second example of a machining devicecontrolled by a central controller but does not include the capacity forchamfering and deburring. U.S. Pat. No. 4,565,081 (Massee) teaches anddescribes a forming machine as yet another example of a memorycontrolled machining device which does not teach or describe chamferingor deburring.

None of these references teaches nor discloses a method to chamfer anddeburr the complex surfaces of a precision spiral gear, together withthe capacity to perform other common machining processes such asdrilling, honing, reaming, polishing and buffing, nor the apparatus tocarry out such a method.

BRIEF DESCRIPTION OF THE INVENTION

The present invention resides in the computer modeling of the topographyof a workpiece, such as a complex gear, by using the data created by aworkpiece inspection program and adapting this data to guide a roboticapparatus to carry out such machining operations as deburring,chamfering, honing, reaming and polishing.

Manufacturing a workpiece such as a complex aerospace gear begins withthe creation of a drawing of the gear in accordance with thespecifications required by the gear designer. Typical specifiedparameters are, for example, the number of gear teeth, the pitch andangle of the teeth, the addendum or dedendum of the gear surfaces, theface angle of the blank, the gear root angle, the outside diameter ofthe gear, and for spiral bevel gears, the direction of the spiral.

A test gear is then manufactured and evaluated. Another software productsupplied by Gleason is the GAGE program which digitally describes thegear tooth topography to create an inspection file. This file is usedwith inspection devices such as the Hoffler-Zeiss machine to inspectfinished gears for accuracy. Any necessary corrections that must be madein order to produce a satisfactory gear are then carried out bymodifying the machine settings.

I have found, surprisingly, that the data created by the GAGE programcan be used to computer-model the gear tooth contours with sufficientaccuracy and specificity to crete a data set that can be used with acomputer controlled robotic arm on which is mounted a selected machiningtool. This data set can be input directly into the program used tooperate the robotic arm. This means that individual points on complexgear contours such as hypoid and spiral bevel gears can be described interms of their x, y and z coordinates with sufficient specificity toguide a machining tool mounted to a robotic control arm to carry outaccurately a finishing operation such as deburring, chamfering,grinding, reaming, honing or polishing. This technique allows thesuccessful modeling of the gear tooth topographies in three dimensionsusing the data from the original CAD file used to create the gear toothdrawings and with sufficient accuracy to allow robotic machining ofcomplex surfaces, i.e., operations such as honing, reaming, chamfering,polishing and the like.

While other software is used with other gear cutting machines, for thepurposes of this description the data file created by the software usedto determine the gear cutting machine settings will be called the “CAGE”file, while the inspection data file used to model the gear topographyand set the x, y and z coordinates for the inspecting machine will bereferred to as the “GAGE” file.

In a preferred embodiment of the present invention, a commerciallyavailable robotic arm, commonly supplied with the operating softwarenecessary to control the movement of the arm is mounted on a worksurface and a commercially available grinder is mounted to the workingend of the robotic arm. A commercially available CNC indexable chuck isalso attached to the work surface and the gear to be deburred orchamfered is mounted on the chuck. A data set created from the GAGE fileis input to the operating software for the robotic arm, making the datareadable by the robot which is then instructed to machine a selectedportion of the gear periphery. When that portion is completed, the chuckrotates to bring a next section of the gear into position for machiningand these operations are repeated until the gear tooth contours,toe-to-heel have been chamfered and deburred.

It is extremely important during these operations to make sure that thechamfered surfaces are continuous and where the machining tool isrequired to undergo a change in orientation to follow a surface that nodivots, nicks or other discontinuities are created because suchdiscontinuities will give rise to stressors which will shorten theoperating life and reliability of the gear. This will requirerepositioning and reorientation of the machining tool to follow the gearcontour and may make it desirable to keep the tool in a firstorientation to machine some surfaces, then reposition the tool andmachine the remaining surfaces, rather than attempting to machine in asingle operation that tracks the surface continuously.

For workpieces that require multiple finishing operations, commerciallyavailable interchangeable tool heads are used so that a first head maybe used for the chamfering and deburring operations then replaced by therobot with a second head to be used, for example, to ream holes orkeyways formed in the workpiece which, in turn, may be replaced by athird head used to polish other surfaces of the workpiece.

Although the deburring and chamfering of a complex hypoid or spiralbevel gear has formed the basis for the foregoing examples, it is alsocontemplated that many other workpieces such as gear casings and jetengine blades and vanes may also be finished using the above describedprocess.

Preferably, the work surface, robotic arm, chuck and associated toolingare enclosed within a cabinet and a filtration system is used to drawair into the cabinet thereby capturing the metallic dust and othermaterial machined from the gear blank and trapping it in the filtrationsystem. A flow of supercooled air is directed at that portion of thegear surface being machined to act as a cooling medium at the point oftool contact without the attendant mess and hazard of using a stream ofliquid coolant such as oil or water-based coolants to cool theworkpiece.

While the following describes a preferred embodiment or embodiments ofthe present invention, it is to be understood that this description ismade by way of example only and is not intended to limit the scope ofthe present invention. It is expected that alterations and furthermodifications, as well as other and further applications of theprinciples of the present invention will occur to others skilled in theart to which the invention relates and, while differing from theforegoing, remain within the spirit and scope of the invention as hereindescribed and claimed. Where means-plus-function clauses are used in theclaims such language is intended to cover the structures describedherein as performing the recited functions and not only structuralequivalents but equivalent structures as well. For the purposes of thepresent disclosure, two structures that perform the same function withinan environment described above may be equivalent structures.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further aspects of the present invention may be more fullyappreciated by considering the accompanying drawings in which a spiralbevel gear will be used as exemplary of the apparatus and methodspreferred to practice the invention. In the drawings, in which likefigures refer to like parts:

FIG. 1 is a perspective view of a spiral bevel gear manufactured by agear cutting machine;

FIG. 2 is a lateral elevation of the gear of FIG. 1;

FIG. 3 is an enlarged detail A of FIG. 2 showing the gear teeth;

FIG. 4 is a perspective view of a work surface to which a robotic armand chuck have been attached;

FIG. 5 is a perspective view of a machining wheel used with theapparatus in FIG. 4;

FIG. 6 is a lateral plan view of the wheel of FIG. 5;

FIG. 7 is a lateral plan view of a first machining tool used to chamferholes or other edges;

FIG. 8 is a lateral plan view of a second machining tool used to chamferholes or other edges;

FIG. 9 is a lateral plan view of a machine tool used to hone holes orother surfaces;

FIG. 10 is a simplified detail of the gear teeth shown in detail Ashowing the repositioning of the machining tool;

FIG. 11 is a perspective view of the arrangement of FIG. 4 as shownmounted in a work cabinet;

FIG. 12 is a schematic view of a gear housing showing various types ofsurfaces to be machined by use of the present invention;

FIG. 13 is a lateral plan view of a stem gear; and

FIG. 14 is a flow diagram of the steps for programming a robotic arm tocarry out selected machining processes.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, the numeral 10 indicates generally a spiral bevelgear formed as a ring having a series of gear teeth 12 cut on an outerrim 14 and having a central opening 16. Gear teeth 12 are identical indimension and configuration and each gear tooth 12 has a toe 18 and aheel 20. The geometry of gear 10 is such that each gear tooth has aconcave surface 22 and a convex surface 24 and is curved toe to heel.

Referring to FIG. 2, it can be seen that rim 14 has a beveled lowersurface 26. Referring to FIG. 3, a portion of the gear in FIG. 2 shownin detail A is enlarged and shows that each gear tooth 12 has at itsheel a heel chamfer 28 formed between heel 20 and gear top land 30. Asalso seen in FIG. 3, adjacent gear tooth 32 has a similar heel chamfer34 formed between heel 20 and top land 38. In the example selected,adjacent gear teeth about the periphery of gear 10 are identical inrelationship as that of adjacent gear teeth 12 and 32.

Gear teeth 12 and 32 form, therebetween, a root 40 generally describedas the bottom of the groove or valley formed between adjacent gear teethand extending heel to toe. Each gear tooth has a tooth profilecomprising, generally, the geometric cross-section of a single geartooth extending between adjacent root surfaces.

Spiral bevel gear 10 is exemplary of a complex gear shape which, whenused in aerospace applications, must have the edges of all gear teethdeburred and chamfered. Each gear tooth will be chamfered across alledges of its heel and toe profile from root to top land and along boththe concave and convex edges of the tooth.

Referring again to FIGS. 2 and 3, a chamfer 42 is formed on gear teeth12 and 32, having a heel root segment 42 a extending from upper land 30to upper land 38, a convex segment 42 b extending along the intersectionof convex surface 22 and top land 38, a toe segment 42 c extending fromchamfer 42 b to the intersection of top land 30 and concave surface 24,and a concave segment 42 d extending along the intersection of top land30 and convex surface 22 to segment 42 a.

Thus, a completed, production quality gear 10 will have chamferedsurfaces following the gear profiles at the heel and toe ends of eachindividual gear tooth as well as chamfers formed at the heel and toeends of the top surfaces or top lands of adjacent gear teeth with alledges free from burrs. In general, the larger the gear tooth the widerthe bevel. Additional operations such as hardening, grinding andpolishing may be required to produce a finished, ready-to-use gear.

Referring to FIG. 4, the numeral 50 indicates generally a machiningapparatus assembled and operated consistent with the characteristics ofthe present invention. A work table 52 supports a horizontal worksurface 54 to which a “table top” robot 56 and an indexable chuck 58 aremounted. One such robot found useful for carrying out the presentinvention is the LR Mate 200i 6-axis electric servo-driven robotmanufactured by FANUC Robotics North America of Rochester Hills Mich.Another is manufactured by ABB Robotics of Zurich, Switzerland. Theseare exemplary of such robots.

Exemplary of an indexable chuck is the HRT series of T-slotted rotarytables manufactured by Haas Automation, Inc. of Oxnard, Calif. Anotheris the compact CNC rotary table manufactured by Nikken Kosakusho Worksof Osaka, Japan.

Referring to FIG. 4, robot 56 has a robot body 60 to which is attachedan articulated arm 62, the motion of which is controlled by a centralprocessing unit (not shown) using control software provided by themanufacturer of table top robot 56. In the present invention,articulated arm 62 has a first arm segment 64 and a second arm segment66 operatively joined at a first universal joint 68. At the outermostend 70 of second arm segment 66, a tool holder 72 is mounted. As will bedescribed below, tool holder 72 operatively engages machining tools ofvarious purposes. For the purposes of this embodiment of the presentinvention, tool holder 72 rotatably holds a machining tool 74. Apreferred embodiment of one such tool is shown in perspective in FIG. 5and a lateral view in FIG. 6. Machining tool 74 has a machining disk 76mounted to an arbor 78 and secured with an arbor nut 80. Tool 74 ismounted to tool holder 72 by securing arbor 78 to tool holder 72 as, forexample, by inserting arbor 78 into a collet or other typical clampingdevice.

Machining tools can be formed in a number of configurations dependingupon the size and maneuverability required to reach and machine theworkpiece surfaces. Tools intended for use as grinders can be formedfrom CBN while cutting tools can be formed from carbide. As seen inFIGS. 7 and 8 grinders 152, 154 are used to chamfer the edgessurrounding the opening of a hole, or other sharp edges, while thereaming or honing tool 156 shown in FIG. 9 is used to finish theinterior surface of a hole.

As seen in FIG. 10, machining tool 74 is shown in two positions, 74A and74B. When machining profile chamfer 42 on gear tooth 12, tool 74 wouldbe positioned in orientation 74A; when machining a chamfer on surface 48of gear tooth 32, tool 74 would be positioned in the orientation shownat 74B. To successfully chamfer the gear tooth edges the machining tool74 must follow the entire gear profile which requires tool 74 toconstantly change orientation to follow the contours, always angled tocreate a chamfer of 45°.

Referring now to FIG. 11, the numeral 82 indicates generally a preferredmachining assembly consisting of a machine tool cabinet 84, air gun unit86 and filtration unit 88. Cabinet 84 is built to enclose worktable 52,robot 56 and chuck 58 and in so doing provides important machiningadvantages.

In the embodiment shown in FIG. 11, cabinet 84 is joined to work table52 and has a left panel 90 a rear panel 92, a right panel 94, a toppanel 96 and a pair of front doors 98, 100 formed of a protectivesheeting material such as Plexiglas®. Doors 98, 100 open to provideaccess to cabinet 84 to allow work pieces to be placed on chuck 58 andthereafter removed when machining is completed. An air inlet 102 ispositioned on left panel 90 to allow ambient air to enter cabinet 84.

Filtration unit 88 has a filtration cabinet 104 within which aredisposed a ventilating fan and a filtration system (not shown). Aflexible air duct 106 extends from filtration cabinet 104 to outlet port108 formed on worktable 52 and, thereby, to the interior of cabinet 84by an exhaust duct not herein specifically shown. When filtration unit88 is activated, air is drawn through inlet 102 and from cabinet 84through flexible duct 106 thereby carrying away dust or other debriscreating during machining operations. Such material is trapped withincabinet 104 by the unit's filters and later removed.

Cooling air gun unit 86 supercools ambient air to about 100° F. belowthe ambient air temperature and blows it through an air line 110 whichis in fluid communication with air a nozzle 112 which forms the terminusof air line 110. Supercooled air is thus directed by nozzle 112 tocontact the workpiece at the point that the workpiece is being machined.The flow of air cools the work piece, dissipates the heat created by theoperation and helps to blow the dust and other debris created bymachining away from the work site and into the cabinet where it can betrapped by filtration unit 88.

An example of a filtration unit 88 preferred for use with the presentinvention is manufactured by Air Flow Systems, Inc. of Dallas, Tex. Anexample of an air gun preferably used in connection with the presentinvention is the model 610 cold air gun unit manufactured by ITW Vortecof Cincinnati, Ohio, which has the capacity for cooling ambient air by100° F.

Although the present invention has principally been discussed in termsof the operations required to machine the gear teeth on an aerospacegear, such as a spiral bevel gear, it is expected that the presentinvention may be useful in machining in other work pieces such as thegear housings, blades and vanes mentioned above. It is expected thatlarger workpieces will require larger cabinets, different cabinetconfigurations, different indexable chucks, different robots andpossible a robot to load and unload workpieces. The operating principlesof the present invention can be applied to these various equipmentconfigurations.

Referring now to FIG. 12, the numeral 118 represents schematically agear housing generally formed from metals such as aluminum or magnesiumor alloys thereof in a casting process. Gear housing 118 has an exteriorsurface 120 and an interior housing surface 122 and, shown asrepresentative of common aspects of such housings, are through hole 124and blind hole 126. Use of the present invention to machine a work piecesuch as housing 118 follows the same principles as that of machiningcomplex gears. A gage file is created from a line or CAD drawing of thehousing and a data set is generated. Even though the housing may be castrather than milled by a computer controlled milling machine, thecontours of the housing are accurately identified and characterized bythe enhanced CAD model, making it possible to program robot 56 to followthe interior or exterior contours of housing 118 and to perform annumber of additional operations such as polishing, buffing, drilling,reaming, deburring and chamfering holes such as through hole 124 orblind hole 126.

To accomplish these tasks, a robot 56 with the capability of changingtools to perform different operations on a single work piece is used.Such robots are well known in the industry and one example of a systemwhich gives such a robot the capability of changing tools to performdifferent operations is the QC-11 Tool Mount and Tool Holder systemmanufactured by ATI Industrial Automation of Apex, N.C. In the presentexample, a deburring tool would be used to debur the exterior surface120 or interior surface 122 of housing 118.

Referring now to FIG. 13 the principles of the present invention areapplied to machine a stem gear 128. Gear 128, shown in section, has adrive stem 130 crowned with a gear 132 having a series of gear teeth 134formed about its upper periphery. Holes 136 are formed through gear 128for purposes of ventilation or to make gear 128 lighter in weight. Anaxial bore 138 is formed therethrough to serve as a mounting channel.

When being machined, gear 128 is held in indexable chuck 140 and, insuccessive operations, robot 56 is used to deburr and chamfer teeth 134,chamfer and ream holes 136 and chamfer and hone bore 138, changing toolswhen necessary to perform other machining operations.

Referring now to FIG. 14 the numeral 142 indicates a flow diagramdetailing the manufacturing steps for complex spiral bevel gears. Atnumeral 144, specifications for the gear to be manufactured arefurnished by the customer in the form of a line or CAD drawing, a set ofwritten specifications detailing such parameters as the number of gearteeth, the pitch and angle of the teeth, the addendum or dedendum of thegear surfaces, the face angle of the blank, the gear root angle, theoutside diameter of the gear, and for spiral bevel gears, the directionof the spiral.

At numeral 146, a gear design engineer generates a series of settingsfrom the specifications by using a computer program such as the CAGEprogram described above. Typically such programs are furnished by themanufacturer of the gear-cutting machine used to manufacture the gear.

At numeral 148 the settings are used to direct the gear cutting machineto manufacture a prototype gear from a metallic blank.

At numeral 150 an inspection data file is created using software such asthe GAGE software described above. The inspection data file is a virtualmodel of the gear tooth cut by the gear cutting machine.

At numeral 152, the inspection data file is used to inspect theprototype gear for accuracy and other manufacturing specifications on atesting machine such as the Hoffler Zeiss machine described above.

At numeral 154 if the prototype is found to be unsatisfactory the gearengineer is notified and, at numeral 156, makes adjustments using theCAGE program and another gear is manufactured at step 148. This cycle isrepeated until a satisfactory prototype gear is produced whereupon, atnumeral 158, the gear is sent to the robotic apparatus described abovefor chamfering and deburring.

To program robot 56 for chamfering and deburring, the correct GAGE fileis used to model the gear within the robot's controlling software at160.

At numeral 162 the gear is robotically chamfered and deburred asdescribed in detail above.

At numeral 164 any required heat treating is carried out. Thereafter, atnumeral 166 the gear teeth are ground by a grinding machine designedspecifically to grind spiral bevel gear teeth.

Finally, at numeral 168 the gear tooth chamfers are polishedrobotically, again using the GAGE file data set to control the roboticpolishing operations.

1. A method for manufacturing a complex spiral gear from a blank, saidmethod comprising the steps of: using a first computer program to createa first data set that identifies the contours of said gear; using saidfirst data set to set the operating parameters of a gear-cuttingmachine; cutting a gear from said blank with said gear-cutting machine;using a second computer program to generate a second data set for thepurpose of measuring and inspecting said gear; measuring and inspectingsaid gear by a gear-inspection machine operated by said second computerprogram; mounting said gear to a rotatable, indexable chuck; using athird computer program to generate a computer model of the contours ofsaid gear, said third computer program adapted to operate said indexablechuck and a robotic work arm; mounting a first selected machining toolon said robotic work arm; using said third computer program to operatesaid work arm to bring said first machining tool into contact with afirst selected portion of said gear contours; conducting a firstmachining operation upon said first gear contour portion; operating saidindexable chuck to bring a second selected portion of said gear contourinto position to be machined; using said third computer program tooperate said work arm to bring said first machining tool into contactwith said second selected portion of said gear contours; conducting saidfirst machining operation upon said second gear contour portion; andcontinuing to reindex and machine said gear until all contours desiredto be machined have been machined.
 2. The method of claim 1 includingthe steps of: removing said first machining tool and replacing it with asecond machining tool to carry out a second machining operation; usingsaid third computer program to operate said work arm to bring saidsecond machining tool into contact with a third selected portion of saidgear contours; conducting said second machining operation upon saidthird gear contour portion; operating said indexable chuck to bring afourth selected portion of said gear contour into position to bemachined; using said third computer program to operate said work arm tobring said second machining tool into contact with said second selectedportion of said gear contours; conducting said second machiningoperation upon said fourth gear contour portion; and continuing toreindex and machine said gear until all contours desired to be machinedhave been machined.
 3. The method of claim 2 wherein said machiningoperation is selected from the group of chamfering deburring, honing,reaming, grinding, polishing, buffing and drilling.
 4. The method ofclaim 1 wherein said machining operation is selected from the group ofchamfering deburring, honing, reaming, grinding, polishing, buffing anddrilling.
 5. A method for manufacturing a complex spiral gear from ablank, said method comprising the steps of: using a first computerprogram to create a first data set that identifies the contours of saidgear; using said first data set to set the operating parameters of agear-cutting machine; cutting a prototype gear from said blank with saidgear-cutting machine; using a second computer program to generate asecond data set for the purpose of measuring and inspecting saidprototype gear; measuring and inspecting said prototype gear with agear-inspection machine operated by said second computer program;correcting any detected errors in said prototype gear by resetting saidgear-cutting machine operating parameters and manufacturing a secondprototype gear; repeating said prototype manufacture and inspectionsteps until a final of said prototype gears meets desired gearspecifications; using a third computer program to generate a computermodel of the contours of said final prototype gear, said third computerprogram adapted to operate an indexable chuck and a robotic work arm;using said gear-cutting machine parameters to cut a production gear;mounting said production gear to said rotatable, indexable chuck;mounting a selected machining tool on said robotic work arm; using saidthird computer program to operate said robotic work arm to bring saidmachining tool into contact with a first selected portion of thecontours of said production gear; carrying out a first machiningoperation upon said first production gear contour portion; operatingsaid indexable chuck to bring a second selected portion of saidproduction gear contour into position to be machined; using said thirdcomputer program to operate said work arm to bring said machining toolinto contact with said second selected portion of said production gearcontours; carrying out said first machining operation upon said secondselected production gear contour portion; and continuing to reindex andmachine said production gear until all contours desired to be machinedhave been machined.
 6. The method of claim 5 wherein a succession ofsaid machining operations are carried out upon said workpiece.
 7. Themethod of claim 5 wherein said machining operation is selected from thegroup of chamfering deburring, honing, reaming, grinding, polishing,buffing and drilling.
 8. Apparatus for manufacturing a workpiece from ablank, said apparatus comprising: a cutting machine having machinesettings adjustable to cut the contours of said workpiece from saidblank; a first computer program to create a first data set thatidentifies said contours of said workpiece, said cutting machinesettings determined by said first data set; an inspection machineadapted to perform measurements upon said workpiece contours, a secondcomputer program to transform said measurements into a second data set;a robotically-controlled machining arm, said arm adapted to receive andoperate a multiplicity of machining tools responsive to a third computerprogram; an indexable chuck adapted to hold said workpiece and rotatesaid workpiece to bring said workpiece into a selected position; a thirdcomputer program to control the movements of said arm and said chuck,said third computer program adapted to use said second data set tocontrol said chuck and said arm whereby a selected of said tools isbrought into contact with a first selected portion of said contours tocarry out a machining operation upon said contour and said chuck isoperated to bring successive portions of said contours into position tobe machined until all contours desired to be machined have beenmachined.
 9. The apparatus as recited in claim 8 further comprising awork cabinet within which said arm and said chuck are positioned. 10.The apparatus as recited in claim 9 further comprising means forcollecting dust and debris created by said machining operation, saidcollecting means including a hood forming the upper portion of saidcabinet, an air inlet formed through said hood; a cabinet base having anair outlet; a vacuum filtration unit; and a duct extending from said airoutlet to said filtration unit.
 11. The apparatus as recited in claim 8further comprising means for cooling said workpiece during saidmachining operation; said cooling means including means for supercoolingambient air; means for directing said supercooled air to impinge uponsaid workpiece proximate the site of said machining operation.
 12. Theapparatus of claim 8 wherein said machining tools include tools to canyout the operations of chamfering, deburring, honing, reaming, grinding,polishing, buffing and drilling.